1. Field of the Invention
This invention relates generally to the field of fertilizer chemistry, and more particularly to products and compositions for regulating plant growth.
2. Description of the Prior Art
Favorable growth media have been obtained by amending subsoil clay with quartz sand or by adding clay to quartz or loamy sands (Albrecht.sup.1 ; Albrecht and Schroeder.sup.2 ; and Del Vale et al..sup.3).
Vermiculite and perlite as amendments have also improved media physical properties and plant growth (Dunham.sup.4 ; Hayes & Simpson.sup.6 ; Mansell et al..sup.8 ; and Warren & Tunny.sup.13).
Peat vermiculite and peat-perlite mixtures have been developed for commercial plant growing (Sheldrake et al .sup.11,12); however, the amendment of these materials with clay has not been reported.
Soilless media generally have low fertility reserves and as nutrient levels are increased, salinity pH and toxicity troubles appear because of insufficient buffering capacity. Trace element imbalances are frequent problems as well. Peat-like mixes are also difficult to wet and they possess low reserves of moisture available to the plant.
Growth media used heretofore in seed-media pots or trays have generally been granular in form, tend to shift within the container in shipment, compact when wet, and shrink away from the container walls when dried. Such growth media are generally intended as germination bedding with the intent of transplating to larger containers and different growth media at a later stage of plant growth. Such starting media are generally incapable of supporting horticultural plant growth to maturity without additional fertilizer applications.
Growth media of the general type have also been described in the patent art. The patent to Clawson, U.S. Pat. No. 2,785,969 teaches a seed planting package consisting of a water retaining medium such as Haydite, vermiculite, pumice and wood pulp chips to which fertilizers are added and held together by an organic binder such as gelatin, methylated cellulose, agar, peat moss and paper. Clawson's mixture is placed in a smelter and heated to a molten mass and then fritted in water. His final product is a fused synthetic vitreous matrix.
The use of vermiculite and perlite to facilitate seed germination and seedling growth has also been described in the patent to Dresser, U.S. Pat. No. 2,909,869. Dresser teaches the use of vermiculite and perlite in direct field seeding of tomato seeds and the like to prevent crusting over of the surface of the soil, which inhibits growth.
Colloidal clay has also been used to form bonded agricultural granules as taught in the patent to Marples, et al. U.S. Pat. No. 3,062,637. These bonded granules are intended to be used as carriers for plant nutrients, herbicides, algicides, and/or insecticidal toxicants. The granular structure facilitates distribution to a site and their hard surface resists attrition in handling.
Clay has been used since the dawn of history as a binder to form bricks and the like, but has never been regarded as a desirable medium for growing plants.